Pelagic Animals Research Articles

Estimating chlorophyll profiles from electronic tags deployed on pelagic animals

Electronic tags deployed on pelagic animals in the ocean are revolutionizing our under- standing of how pelagic species interact with the physical environment, by making simultaneous eco- physiological and in situ oceanographic measurements at relatively low cost. Pelagic animals with electronic tags are also increasingly being used as ocean sensing platforms. Here, we demonstrate the concept of estimating in situ chlorophyll concentration profiles from light level and depth data collected by electronic tags, using a bio-optical model. We assessed this concept by deploying elec- tronic tags at 14 oceanographic stations in the Pacific Ocean, together with a fluorometer and Niskin bottles. In the euphotic zone, tag-estimated chlorophyll concentrations correlated significantly with simultaneous chlorophyll concentration measurements from filtered water samples (R 2 = 0.41, p < 0.0001) and a profiling fluorometer (R 2 = 0.29, p < 0.0001). Below the euphotic zone, peaks in the light attenuation profile corresponded to deep scattering layers, with a 17 m rms difference between the deep scattering layer depths estimated by the tags and an Acoustic Doppler Current Profiler. In situ chlorophyll profiles were also derived from electronic tags deployed on Pacific bluefin tuna in Baja California waters, and found to be comparable to chlorophyll profiles in the World Ocean Database for the region and season. Although more research is needed to improve this approach, the results from both shipboard and Pacific bluefin tuna experiments indicate that light level attenuation profiles derived from electronic tags can be successfully used to estimate chlorophyll concentration profiles.

Relative importance of vascular plants and algal production in the food web of a Spartina-invaded salt marsh in the Yangtze River estuary

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 367:93-107 (2008) - DOI: https://doi.org/10.3354/meps07566 Relative importance of vascular plants and algal production in the food web of a Spartina-invaded salt marsh in the Yangtze River estuary X. Shang1,2,*, G. S. Zhang1, J. Zhang1 1State Key Laboratory of Estuarine and Coastal Research, East China Normal University, 3663 Zhongshan Road North, Shanghai 200062, PR China 2School of Environment and Public Health, Wenzhou Medical College, Wenzhou 325035, PR China *Email: archershang@hotmail.com ABSTRACT: The trophic importance of microphytobenthos (MPB), phytoplankton, C3 vascular plants and invasive Spartina alterniflora in benthic and pelagic food webs was studied in Jiuduansha, a newly formed salt marsh in the Yangtze River estuary, using natural stable carbon and nitrogen isotopic analyses and IsoSource evaluation. MPB was found to be the major food source of meiofauna and important in the diets of macrofaunal consumers. Carbon derived from C3 vascular plants significantly contributed to the nutrition of all planktonic copepods and supported planktivorous nekton, but played a minor role in the benthic food web. Although phytoplankton could be utilized by all the consumers, low production in this highly turbid estuary might restrict its relative importance. High trophic-level consumers could get carbon from 13C-enriched MPB and 13C-depleted C3 plants via zoobenthos and zooplankton, respectively. Neither benthic nor pelagic animals fed exclusively on S. alterniflora except for a gastropod species in the present study, indicating a minor contribution of this invasive C4 plant to the food web of the Jiuduansha salt marsh. In light of the degradation of salt marshes in the Yangtze River estuary, the rapid expansion of this invasive C4 plant may alter the nutrient foundation of resident and migratory consumers and thus significantly impact the ecosystem there. KEY WORDS: Salt marsh · Food web · Microphytobenthos · Spartina alterniflora · Invasion · Trophic shift Full text in pdf format PreviousNextCite this article as: Shang X, Zhang GS, Zhang J (2008) Relative importance of vascular plants and algal production in the food web of a Spartina-invaded salt marsh in the Yangtze River estuary. Mar Ecol Prog Ser 367:93-107. https://doi.org/10.3354/meps07566 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 367. Online publication date: September 11, 2008 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2008 Inter-Research.

Life strategy of pelagic animals in Lake Baikal

Life strategy of pelagic animals in Lake Baikal

Light scattering by selected zooplankton from the Gulf of Aqaba

Light scattering by zooplankton was investigated as a major factor undermining transparency camouflage in these pelagic animals. Zooplankton of differing transparencies--including the hyperiid amphipod Anchylomera blossevillei, an unknown gammarid amphipod species, the brine shrimp Artemia salina, the euphausiid shrimp Euphausia diomedeae, the isopod Gnathia sp., the copepods Pontella karachiensis, Rhincalanus sp. and Sapphirina sp., the chaetognath Sagitta elegans and an enteropneust tornaria larva--were illuminated dorsally with white light (400-700 nm). Spectral measurements of direct transmittance as well as relative scattered radiances at angles of 30 degrees , 90 degrees , 150 degrees and 180 degrees from the light source were taken. The animals sampled had transparencies between 1.5% and 75%. For all species, the highest recorded relative scattered radiance was at 30 degrees , with radiances reaching 38% of the incident radiance for the amphipod A. blossevillei. Scattering patterns were also found to be species-specific for most animals. Relative scattered radiances were used to estimate sighting distances at different depths. These calculations predict that all of the examined zooplankton are brighter than the background radiance when viewed horizontally, or from diagonally above or below at shallow depths. Thus, in contrast to greater depths, the best strategy for detecting transparent zooplankton in the epipelagic environment may be to search for them from above while looking diagonally downwards, looking horizontally or looking from below diagonally upwards. Looking directly upwards proved to be more beneficial than the other viewing angles only when the viewed animal was at depths greater than 40 m.

Blood Culture Results from Healthy Captive and Free‐Ranging Elasmobranchs

Blood culture is a diagnostic tool used in confirming bacterial disease in teleostean and elasmobranch fishes. Unlike teleosts, elasmobranchs have a normal microflora in multiple organs, but their blood has generally been considered to be sterile. In regular exams of elasmobranchs conducted at a public aquarium, occasional blood samples have tested positive on culture. This finding prompted a blood culture survey of healthy captive and wild elasmobranchs (sharks and stingrays), which showed that 26.7% of all animals were positive. Stingrays alone showed a 50% occurrence of positive blood cultures, although the total number of animals was low and freshwater species were included in this number. When elasmobranchs other than stingrays were evaluated according to metabolic category, pelagic animals had a higher percentage of positive cultures than nonpelagic animals (38.7% versus 13.9%). These results indicate that a single positive blood culture without other corroborating diagnostics is not sufficient to confirm septicemia in elasmobranchs.

Depth‐related trends in metabolism of benthic and benthopelagic deep‐sea fishes

The metabolism of several animal groups declines with depth even after adjustments for size and temperature. The “visual‐interactions hypothesis” explains this trend as the result of declining light levels that reduce the distances over which predators and prey interact. This reduction relaxes the selective pressure for locomotory capacity, and reductions in metabolic rate follow. The decline in visual interactions and metabolism is most pronounced among pelagic species, as this environment affords no refuge from predators. The visual‐interactions hypothesis thus predicts less depth‐related variation among benthic species. However, it has been tested primarily with pelagic animal data. Summarizing many scattered studies and data sets to further test the hypothesis, here we analyze the data for benthic and benthopelagic fishes. Oxygen consumption rates declined significantly with depth in benthopelagic and, to a lesser extent, benthic species. Trends in muscle metabolic enzyme activities generally corroborated these patterns. The anaerobic capacity of the white muscle indicated the greatest decline in pelagic and the smallest reduction in benthic species, as expected. Similar trends were not found in aerobic capacity, but this result may reflect a paucity of enzyme data for benthic species. Most of the studied fishes live off of California, where the presence of an oxygen‐minimum zone may influence some of the patterns observed. This preliminary analysis of data clearly illustrates that temperature and body mass cannot explain the variability evident in metabolism. Rather, some covariate of habitat depth acts to influence metabolism in benthic and benthopelagic fishes. The general trends are explained by the visual‐interactions hypothesis, but considerably more data are required to account for the variation in metabolism and lifestyle that is apparent. In particular, regional comparisons are needed to separate the influences of environmental factors, such as oxygen, which covary with depth.

Branchial morphology and ion–water transport proteins in Antarctic teleosts with different modes of life

In the Antarctic Ocean salt concentration differs from the bottom to the surface owing to the seasonal forming and melting of sea ice. Antarctic teleosts present different lifestyle from benthic to pelagic. While benthic animals face a constant seawater salinity, benthic–pelagic animals have to face different salt concentration. Branchial morphology and ion–water transport proteins were compared in animals with different lifestyle. The ultrastructure of the gills was investigated by scanning electron microscopy (SEM). Na+/K+/ATPase, Na+/K+/Cl− cotransport protein NKCC1 and Aquaporin 3 (AQP3), were investigated by immunohistochemistry. The immunoreactivity for the ion transporter proteins were more intense in the active benthic–pelagic animals and in the icefishes than in the sluggish benthic ones. Conversely, AQP immunoreactivity was stronger in the animals with sedentary lifestyles. The SEM showed the secondary lamellae in the benthic–pelagic animals more densely packed with the exception of the haemoglobin free teleosts.

MECHANICS OF REMORA REMOVAL BY DOLPHIN SPINNING

Marine Mammal ScienceVolume 23, Issue 3 p. 707-714 MECHANICS OF REMORA REMOVAL BY DOLPHIN SPINNING Daniel Weihs, Daniel Weihs Faculty of Aerospace Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel E-mail: dweihs@techunix.technion.ac.ilSearch for more papers by this authorFrank E. Fish, Frank E. Fish Department of Biology, West Chester University, West Chester, Pennsylvania 19383, U.S.A.Search for more papers by this authorAnthony J. Nicastro, Anthony J. Nicastro Department of Physics, West Chester University, West Chester, Pennsylvania 19383, U.S.A.Search for more papers by this author Daniel Weihs, Daniel Weihs Faculty of Aerospace Engineering, Technion, Israel Institute of Technology, Haifa 32000, Israel E-mail: dweihs@techunix.technion.ac.ilSearch for more papers by this authorFrank E. Fish, Frank E. Fish Department of Biology, West Chester University, West Chester, Pennsylvania 19383, U.S.A.Search for more papers by this authorAnthony J. Nicastro, Anthony J. Nicastro Department of Physics, West Chester University, West Chester, Pennsylvania 19383, U.S.A.Search for more papers by this author First published: 11 June 2007 https://doi.org/10.1111/j.1748-7692.2007.00131.xCitations: 24Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume23, Issue3July 2007Pages 707-714 RelatedInformation

The chemistry of suspended particulate material in a highly contaminated embayment of Port Jackson (Australia) under quiescent, high-wind and heavy-rainfall conditions

This study investigated physico-chemical characteristics of the water column and chemistry of suspended particulate material (SPM) under quiescent, high-wind and high-wind/heavy-rainfall conditions in Homebush Bay, a highly contaminated embayment of Port Jackson (Australia) to distinguish source and possible adverse effects to benthic and pelagic animals. Mean concentrations in surficial sediment were <1, 14, 181, 141, 37, 290 and 685 μg g−1 for Cd, Co, Cr, Cu, Ni, Pb and Zn, respectively. Sediment chemistry indicated these metals had multiple sources, i.e. the estuary, stormwater and industry. Mean total suspended solids (TSS) were 7, 17 and 20 mg L−1 during quiescent, high-rainfall and heavy rainfall/high wind conditions, respectively, whereas SPM Cd, Co, Cr, Cu, Ni, Pb and Zn concentrations varied between 13–25, 166–259, 127–198, 38–82, 236–305 and 605–865 μg g−1, respectively under these conditions. TSS and total water metal concentrations were lowest during quiescent conditions. High TSS and metal loads in surface water characterised high-rainfall events. Wind-induced resuspension contributed the greatest mass of SPM and metals to the water column. Benthic animals may be adversely affected by Pb and Zn in sediment. Total water Cu and Zn concentrations may pose a risk to filter-feeding animals in the water column due to resuspension of contaminated sediment.

Biological and physical forcings of late summer chlorophyll blooms at 30°N in the oligotrophic Pacific

Large chlorophyll blooms have been observed with ocean color satellite data in late summer near 30°N, 135–155°W in the oligotrophic subtropical Pacific. Although blooms do not develop every year, their timing and location are consistent when they do appear. Their biological and physical forcings are unknown. Here we examine biological and physical data from a number of cruises along 30°N in the eastern Pacific between 1980 and 2004, focusing on biological data from a cruise that fortuitously sampled a small chlorophyll bloom in July 2002. The climatological bloom location is characterized by elevated levels of Rhizosolenia diatom mats as well as endosymbiotic and unicellular nitrogen fixation. We conclude that nitrogen fixation and the vertical migration of Rhizosolenia diatom mats below the nutricline are likely mechanisms for the supply of new nitrogen to fuel the chlorophyll blooms and that both mechanisms could be at work. The blooms occur in the eastern gyre of the North Pacific, a region characterized by converging weak surface currents that create an environment favorable for accumulation of positively buoyant particles such as Rhizosolenia mats. These blooms could have important ecosystem consequences by impacting local carbon fluxes and serving as an aggregation point for pelagic animals.

Studies of ecological diversity of pelagic animals in Lake Baikal, Russia

Studies of ecological diversity of pelagic animals in Lake Baikal, Russia

Vertical habitat utilization by large pelagic animals: a quantitative framework and numerical method for use with pop‐up satellite tag data

AbstractA quantitative framework and numerical methodology were developed to characterize vertical habitat utilization by large pelagic animals and to estimate the probability of their capture by certain types of fishing gear. Described are the steps involved to build ‘vertical habitat envelopes’ from data recovered from an electronically tagged blue marlin (Makaira nigricans) as well as from a longline fishing gear experiment employing temperature–depth recording devices. The resulting vertical habitat envelopes, which integrate depth and temperature preferences of tagged fish, are conducive for comparative studies of animal behavior and for calculation (and visualization) of degrees of overlap – be it among individuals, species or fishing gear. Results of a computer simulation evaluation indicated our numerical procedure to be reliable for estimating vertical habitat use from data summaries. The approach appears to have utility for examining pelagic longline fishing impacts on both target and non‐target species and could point to ways of reducing bycatch via modification of fishing strategy or gear configuration.

The 3/4-Power Law Is Not Universal: Evolution of Isometric, Ontogenetic Metabolic Scaling in Pelagic Animals

It is commonly assumed that metabolic rate scales with body mass to the 3/4 power. However, during ontogeny, the metabolic rate of pelagic (open-water) animals often scales isometrically (in a 1:1 proportion) with body mass. This is a robust pattern, occurring in five different phyla. It can also be seen by comparing pelagic and benthic (bottom-dwelling) species within phyla, as well as pelagic larvae and benthic adults within species. High energy costs of continual swimming to stay afloat or of rapid rates of growth and reproduction in response to high levels of mortality (predation) in open water, or both, may contribute to the isometric or nearly isometric metabolic scaling of pelagic animals. The observation of isometric scaling and other kinds of metabolic scaling both within and among species suggests that metabolic scaling is not simply the result of physical constraints, but is an evolutionarily malleable trait that responds to ecological circumstances.

Immunochemical recognition of gelatinous zooplankton: an application to identify the origin of the ‘barrel’: made by the pelagic amphipod, Phronima sedentaria

A first trial to recognize gelatinous zooplankton using an immunochemical method was carried out. Polyclonal antibodies (rabbit IgG) raised against three cnidarians and four pelagic tunicates were purified and tested for their specificity against various sympatric zooplankton and micronekton. While antibodies to cnidarians were species-specific or at least distinguishable by means of the patterns of the bands appearing, antibodies to the pelagic tunicates cross-reacted with the antigen from the other tunicate species although these did not cross-react with other animal taxa. These results suggest that the present cnidarian antibodies can be applied to the predator identification at the species level. Antibodies to pelagic tunicates would also be effective tools for basic scanning at higher taxonomic levels, i.e. pelagic tunicates or other animals. The antibodies were applied to the identification of the ‘barrel’ of Phronima, indicating that the ‘barrels’ originated from tunicates but not from cnidarians. The present study indicates that the immunochemical method using polyclonal antibodies is a powerful tool for the detection of gelatinous zooplankton.

Physiological Ecology in the 21st Century: Advancements in Biologging Science

Top pelagic predators such as tunas, sharks, marine turtles and mammals have historically been difficult to study due to their large body size and vast range over the oceanic habitat. In recent years the development of small microprocessor-based data storage tags that are surgically implanted or satellite-linked provide marine researchers a novel avenue for examining the movements, physiology and behaviors of pelagic animals in the wild. When biological and physical data obtained from the tags are combined with satellite derived sea surface temperature and ocean color data, the relationships between the movements, behaviors and physical ocean environment can be examined. Tag-bearing marine animals can function as autonomous ocean profilers providing oceanographic data wherever their long migrations take them. The biologging science is providing ecological physiologists with new insights into the seasonal movements, habitat utilization, breeding behaviors and population structures in of marine vertebrates. In addition, the data are revealing migration corridors, hot spots and physical oceanographic patterns that are key to understanding how organisms such as bluefin tunas use the open ocean environment. In the 21st century as ecosystem degradation and global warming continue to threaten the existence of species on Earth, the field of physiological ecology will play a more pivotal role in conservation biology.

Vertical distribution of macroplankton at the Charlie-Gibbs Fracture Zone (North Atlantic), as observed from the manned submersible ?Mir-1?

Direct observations of the plankton vertical distribution performed from a manned submersible were made in the Charlie-Gibbs Fracture Zone (Atlantic Ocean). Plankton was counted using a standard 3-m2 frame in the depth layer from 170 to 4361 m and plotted for every 50 m. The most abundant components of the macroplankton were pelagic shrimps, chaetognaths and gelatinous animals, with peak of densities corresponding to the main pycnocline. Mucous houses of appendicularians were abundant at 150 m above the seabed—up to 0.07–0.09 m−3, compared to 0–0.006 m−3 in the upper layers. The new observations confirm that the near-bottom peak of appendicularian abundance is characteristic of at least the entire Central Atlantic, and it is not associated with certain biotopes on the bottom.

Validation of geolocation estimates based on light level and sea surface temperature from electronic tags

Electronic tags have enhanced our understanding of the movements and behavior of pelagic animals by providing position information from the Argos system satellites or by geolocation estimates using light levels and/or sea surface temperatures (SSTs). The ability to geolocate animals that remain submerged is of great value to fisheries management, but the accuracy of these geoloca- tion estimates has to be validated on free-swimming animals. In this paper, we report double-tagging experiments on free-swimming salmon sharks Lamna ditropis and blue sharks Prionace glauca, tagged with satellite telemetry and pop-up satellite tags, which provide a direct comparison between Argos positions and geolocation estimates derived from light levels and SSTs. In addition, the Argos- based pop-up satellite tag endpoints and GPS-based recapture locations of Atlantic bluefin tunas Thunnus thynnus were compared with the last geolocation estimates from pop-up satellite and archival tags. In the double-tagging experiments, the root mean square errors of the light level lon- gitude estimates were 0.89 and 0.55°; while for SST latitude estimates, the root mean square errors were 1.47 and 1.16° for salmon sharks and blue sharks respectively. Geolocation estimates of Atlantic bluefin tuna, using archival data from surgically implanted archival tags or recovered pop-up satel- lite tags, had root mean square errors of 0.78 and 0.90° for light level longitude and SST latitude esti- mates, respectively. Using data transmitted by pop-up satellite tags deployed on Atlantic bluefin tunas, the light level longitude and SST latitude estimates had root mean square errors of 1.30 and 1.89°, respectively. In addition, a series of computer simulations were performed to examine which variables were most likely to influence the accuracy of SST latitude estimates. The simulations indi- cated that the difference between the SST measured by the electronic tag and the remotely sensed SST at a given location was the predominant influence on the accuracy of SST latitude estimates. These results demonstrate that tag-measured SSTs can be used in conjunction with light level data to significantly improve the geolocation estimates from electronic tags.

Revision of the Cambrian discoidal animals Stellostomites eumorphus and Pararotadiscus guizhouensis from South China

The discoidal fossils identified as Stellostomites eumorphus Sun & Hou, Rotadiscus grandis Sun & Hou and Rotadiscus guizhouensis Zhao & Zhu are abundant in the Cambrian Chengjiang and Kaili Lagerstätten of southwest China. Reinvestigation of all available specimens of S. eumorphus and R. guizhouensis indicates that S. eumorphus has radiating lobe structures different from those of Eldonia ludwigi Walcott and has one additional set of dorsal radiating canals, and has a distinct central cavity, two characters that are not present in E. ludwigi. R. guizhouensis differs from R. grandis in the morphology of the disc, internal radiating lobes and tentacles. This supports the validity of the genus Stellostomites Sun & Hou, 1987, and substantiates the erection of a new genus, Pararotadiscus nov. gen., to receive Rotadiscus guizhouensis Zhao Zhu, 1994. Anatomical and taphonomical analyses indicate that S. eumorphus and P. guizhouensis were gregarious pelagic animals. The new anatomical information emphasize close phylogenetic relations with lophophorates (U-shaped intestine, circumoral tentacles and ectodermal, marginal accreted disc), though some features (e.g. dendritic tentacles, ventral pustules that may relate to reduced podia) do not exclude affinitics with echinoderms.

Mortality of marine planktonic copepods: global rates and patterns

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 230:195-209 (2002) - doi:10.3354/meps230195 Mortality of marine planktonic copepods: global rates and patterns A. G. Hirst1,*, T. Kiørboe2 1Department of Biological Sciences, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, United Kingdom 2Danish Institute for Fisheries Research, Charlottenlund Castle, 2920 Charlottenlund, Denmark *Present address: British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, United Kingdom. E-mail: aghi@bas.ac.uk Supplementary Appendices ABSTRACT: Using life history theory we make predictions of mortality rates in marine epi-pelagic copepods from field estimates of adult fecundity, development times and adult sex ratios. Predicted mortality increases with temperature in both broadcast and sac spawning copepods, and declines with body weight in broadcast spawners, while mortality in sac spawners is invariant with body size. Although the magnitude of copepod mortality does lie close to the overall general pattern for pelagic animals, copepod mortality scaling is much weaker, implying that small copepods are avoiding some mortality agent/s that other pelagic animals of a similar size do not. We compile direct in situ estimates of copepod mortality and compare these with our indirect predictions; we find the predictions generally match the field measurements well with respect to average rates and patterns. Finally, by comparing in situ adult copepod longevity with predation-free laboratory longevity, we are able to make the first global approximations of the natural rates of predation mortality. Predation and total mortality both increase with increasing temperature; however, the proportion that predation makes of total adult mortality is independent of ambient temperature, on average accounting for around 2Ž3 to 3Ž4 of the total. KEY WORDS: Copepod · Mortality · Fecundity · Development time · Sex ratio · Temperature · Body mass · Scaling · Predation Full text in pdf format Supplementary Appendices PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 230. Online publication date: April 05, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Critical aspects of the Falkland Islands pelagic ecosystem: distribution, spawning and migration of pelagic animals in relation to oil exploration

1. The oceanography and topography of the southern Patagonian shelf, with the strong Falkland current deriving from the Antarctic Circumpolar current moving northwards both west and east of the Falkland Islands, creates an area of very high zooplankton productivity immediately to the north of the islands. 2. Information on the distribution, spawning times and larval distribution of the most important fish and squid species is reviewed in this paper. High densities of macroplanktonic euphausid and hyperiid amphipods, especially in the summer, attract and sustain squid stocks (the pelagic Illex argentinus and bentho-pelagic Loligo gahi) and pelagic fish (Micromesistius australis and Sprattus fuegensis). 3. There is an important spawning ground for three fish species having pelagic eggs and larvae (Micromesistius australis, Salilota australis and Sprattus fuegensis) on the shelf break immediately to the south and southwest of the Islands. The shelf surrounding the islands, and west and south towards the Argentine coast, forms a nursery area for the larvae of these and a number of other fish and squid species. 4. Pollution emanating from the oil exploration tranches to the north of the islands or oil-based activities on the north shores of the Islands, although coincident with the area of high plankton productivity, would be unlikely to affect, in any major way the pelagic ecosystem around the Falkland Islands unless it became entrained in the area of slack water to the north of East Falkland. However, water flows from the Special Co-operation Area over critical spawning areas for a number of fished species (red cod, southern blue whiting and L. gahi) and has the potential to affect not only these but the Falkland shelf waters which act as a nursery area for many marine species. Copyright © 2002 John Wiley & Sons, Ltd.